HDPE LLDPE LDPE PP PVC

COMMODITY

ENGINEERING

NYLON 12 TPUPC

ACETALTPE/TPV

NYLON 11PEBAXPET

ULTRA ENGINEERING

PEEKPAEK

PPSUPEI

PESUPSU

PI

FEPLCP

PTFE

There has been a profound shift in the medical industry

where procedures have aimed to become more minimally

invasive, quicker and more effective. The goal of this shift

is to minimize patient recovery times, reduce the size of

access incisions and to provide better patient outcomes

through advanced medical procedures. These new

methods necessitate new medical devices that tend to be

more demanding of their components than in devices past.

This requires medical devices and their components to use

updated and advanced polymers. Many of these advanced

materials fall under the general description of high

heat polymers. We will refer to the high heat polymers

discussed here as “ultra-engineering polymers” to identify

that they reside at the pinnacle of performance within the

engineering polymer designation. There are a wide range

of these ultra-engineering high heat polymers but many

of them are somewhat new to the plastics industry and

some are relatively uncommon. Unfamiliarity with ultra-

engineering polymers can prove challenging in choosing

the ideal material for today’s demanding and cutting-edge

medical devices and components. I will identify several of

the more common ultra-engineering polymers, potential

applications, their general properties and their positive

aspects and limitations. This white paper aims to inform all

those responsible for choosing and specifying materials

for devices and extruded components about the variety of

ultra-engineering polymers that are available, so the ideal

material can be chosen for your device.

Ultra-engineering polymers fall under the general

classification of engineered polymers yet they are at the

pinnacle of performance for all thermoplastics (Figure 1).

Ultra-engineering polymers bridge the performance gap

between standard engineering polymers, such as nylon

and polycarbonate; and metals, composite materials

and thermoset plastics like polyimide. Their description

of “high heat polymer” indicates not only that these

materials are processed at higher temperatures, typically

between 600° F and 750° F +, but that they subsequently,

also have high continuous operating temperatures, most

well over 300° F. Ultra-engineering polymers have very

good chemical resistance which makes them ideal for

the hospital environment and the many harsh chemicals

and drugs that plastics can be exposed to. The physical

properties of ultra-engineering polymers also out

perform all other standard engineered polymers in the

areas of tensile strength, flexural strength and impact

resistance. Additionally, these materials have good

dielectric properties and have some level of inherent

flame resistance without additives. All the materials to

be discussed in this white paper have USP Class VI and

ISO 10993 approvals and some have permanent implant

approved grades as well as MAF support.Figure 1. Materials Pyramid

Spectrum Plastics Group White Paper

How to Choose the Ideal Ultra Engineering Polymer for Your Extruded Medical Applicationby Jonathan Jurgaitis —Senior Extrusion Engineer, Apollo Medical Extrusion

Polymer Common PropertiesThe materials discussed here have some common

properties and abilities as well drawbacks that will

be touched on here with material specific properties

being addressed in their section. High heat polymers

can be extruded into large diameter and micro-bore

tubing configurations, thin walls, multi-lumens, solid

rods/mandrels, complex profiles and filament. High

heat polymers can be colored and compounded with

additives such as radiopacifiers, electrically and thermally

conductive additives and various types of physical

reinforcements. They can also be thermally formed and

reflowed for catheter applications as well as RF welded

providing for easier assembly and connection methods

than stainless steel.

High heat polymers are more expensive than most standard

engineering materials and even more expensive than

commodity materials. Implant grades of these materials

can be exponentially more expensive than their standard,

medical grade versions. When high heat materials are

compounded, their costs can double or triple, further

increasing material costs. Because of their high processing

temperatures, some colorant components and additives

can be limited because some of those constituents cannot

withstand the elevated processing temps therefore limiting

the number of possible colors and PMS matching. Several

of these high heat polymers do not have neutral natural

colors which will also affect color matching.

PEEKCurrently the “buzz” material for high requirement plastic

medical applications is PEEK (polyetheretherketone). PEEK

is the highest performing, commercial polymer, it is no

wonder that it is specified in so many high requirement

applications. There are many aspects of PEEK that make

it the ideal choice for some applications. PEEK is a semi-

crystalline material which contributes to some of its best

in class properties, its properties are also optimized in

its semi-crystalline state. Semi-crystalline polymers, like

PEEK, have a portion of their molecules align and form

crystals during proper processing. PEEK has some of the

highest tensile and flexural strength of all commercial, non-

reinforced thermoplastics. This translates to great push-

ability and torque functionality in catheter components and

access devices. PEEK also has very low elongation and

great compressive strength, as well as excellent chemical

resistance to hospital solvents, wipe down chemicals

(Solvay Specialty Polymers 2015), and harsh drugs. PEEK

has good dielectric and insulative properties as well as a

high continuous operating temperature of 465° F or more

which makes it a great choice for ablation procedures.

Its low surface energy finish and hardness makes PEEK a

good choice for artherectomy devices. PEEK is fairly inert

and bio-stable which can reduce the possibility of negative

patient reactions. PEEK is unique in that it has similar

physical properties and density to cortical bone (Solvay

Specialty Polymers 2015). It also doesn’t have degradation

or sensitivity issues like that of titanium as well as not having

reactivity to MRI procedures which makes PEEK ideal for

bone and dental permanent implants (Solvay Specialty

Polymers 2015); permanent implant grades of PEEK are

available for these types of applications but require an

intensive approval process for their use and come with

extremely high costs. PEEK has excellent resistance to

all major sterilization techniques in 100 cycles or more

and 1000 + cycles of steam sterilization (Solvay Specialty

Polymers 2015). All these properties combined allow PEEK

to occupy a unique position as a material suitable for one

time use devices but also for durable devices that will be

reused multiple times.

There is no such thing as a perfect or universal polymer, so

PEEK does have some restrictions to keep in mind while

considering it in your next device. PEEK is the highest cost

raw material of all the materials discussed here, with implant

grades being many times more expensive. PEEK has an

opaque beige appearance which may not be aesthetically

pleasing for some users. This opaque beige color also can

limit how well it can be colored, especially light colors,

and how vibrant bright colors may appear. PEEK requires

special surface preparation prior to printing, usually plasma.

Reflow processes with PEEK can be more difficult than other

materials because of the high processing temperature and

high crystallinity. While PEEK is extremely strong, it is not as

“tough” and ductile as other high heat polymers.

PAEKThere is another high heat, semi-crystalline polymer in

the PEEK family called PAEK (polyaryletherketone). This

material can be utilized as an alternative to PEEK with an

approximate 20% to 30% raw material cost savings. PAEK

has similar physical, thermal and chemical properties

(Solvay Specialty Polymers 2016) as PEEK but with improved

toughness and ductility (Solvay Specialty Polymers 2015—

Figure 2). PAEK also has similar restrictions as PEEK.

Amorphous PolymersThe remainder of the ultra-engineering polymers to be

discussed are all amorphous and range from transparent to

clear in appearance (Figure 3). An amorphous polymer does

not have a distinct melting point and no crystalline structure.

The amorphous ultra-engineering polymers to be discussed

are PPSU, PSU, PESU and PEI (Solvay Specialty Polymers

2016).

PPSUPPSU (polyphenylsulfone) has the highest heat resistance

of all the sulfones and PEI (polyetherimide). PPSU has a

continuous operating temperature of about 400° F, which

allows it to handle some of the same high heat applications

as PEEK. PPSU is very hydrolytically stable which enables

it to excel in high heat and humidity environments. PPSU is

highly chemical resistant to all hospital solvents and wipe

down chemicals (Solvay Specialty Polymers 2015) and also

can withstand 100 or more cycles of all sterilization methods

as well as 1000 + cycles of steam sterilization (Solvay

Specialty Polymers 2015). These properties along with its

transparency allows this material to also bridge the gap

between one time use and durable devices where the ability

to see the placement or position of catheters or endoscopy

tools, or the flow of fluids is critical to the functionality of the

device and procedure. PPSU has very high ductility which

is quantified by the lowest tensile and flexural strengths of

all the materials discussed here. This high ductility positions

this material as a candidate for steerable catheters and

catheters that need to follow torturous paths through the

body while still having need of high heat and chemical

resistance. Permanent implant grades of PPSU are available

for applications such as wire lead coatings, fluid transfer and

orthopedics (Solvay Specialty Polymers 2015).

PPSU has the highest raw material costs of these

amorphous materials but it is still less expensive than PEEK.

PPSU has a transparent amber appearance which may

not be aesthetically pleasing for some users. However,

the amber color appears less pronounced in thin wall and

micro-bore configurations. This transparent amber color can

limit how well it can be colored, especially light colors, and

may affect how vibrant bright colors may appear.

Figure 2. Ultra-Polymers PAEK comparison PEEK

Figure 3. Transparent Polymer Comparison

PSUThe strength and toughness of the amorphous

materials start to increase from this point forward. PSU

(polysulfone) is a high strength sulfone material with

greatly improved clarity over PPSU. PSU has the lowest

continuous operating temperature of all these high heat

polymers at about 340° F, but it is still considerably higher

than other common engineered polymers. PSU has

good chemical resistance to many hospital chemicals

(Solvay Specialty Polymers 2015) and is hydrolytically

stable for hot and humid environments (Solvay Specialty

Polymers 2015). It can withstand 40 kGy of Gamma

and up to 100 cycles of all other sterilization methods

(Solvay Specialty Polymers 2015). PSU can be a choice

for a durable component but doesn’t have as long of a

life span in some environments as the other materials

covered here. PSU’s properties position it as a great,

higher end replacement for polycarbonate. PSU has

better chemical resistance, higher hydrolytic stability, and

much higher temperature resistance than polycarbonate

(Solvay Specialty Polymers 2015). Even though PSU can

have a slight yellowish tint to it, PSU still has good clarity

while most grades of medical polycarbonate need to

have a noticeable purplish tint to them to compensate

for color shifts during Gamma sterilization. PSU has good

ductility and better toughness. PSU is a good option for

dental tools and components because of its toughness

and hydrolytic stability. PSU comes in permanent implant

grades that are not suitable for structural components

but can be used in applications where ductility, strength,

toughness and clarity are necessary.

PSU has good clarity, so it can be colored to transparent

and opaque colors and be more accurately color matched,

provided color constituents can withstand processing

temperatures. Raw material prices for PSU are moderate,

about 50% to 75% higher than polycarbonate and similar to

prices for PEI and PESU.

Some of the limitations of PSU are: it does have decreased

sterilization and chemical resistance compared to the other

ultra-engineering polymers that are discussed here. PSU

also has lower tensile and flexural properties than PESU and

PEI but are higher than PPSU.

PESUAnother member of the sulfone family that has high

potential for use in medical applications is PESU (polyether

sulfone). PESU has the highest tensile and flexural strength

of the sulfones listed here as well as excellent clarity.

PESU has better chemical resistance to hospital solvents

and disinfectants and has good hydrolytic stability (Solvay

Specialty Polymers 2014). In combination with PESU’s

continuous operating temperature of about 390° F, these

properties make it a good candidate for harsh applications

where high strength and clarity are needed. Applications

such as sight windows and patient access components

where being able to see fluid movement, and device

location and position are necessary. Because of the

stiffness and hardness of PESU it has good pushability and

torque properties that can potentially eliminate braiding

and other reinforcement methods in some applications.

PESU has just slightly decreased physical and thermal

properties compared to PEI which makes it a good option

for replacement of PEI while adding greatly improved

clarity. PESU is also an option as a much higher performing

alternative to polycarbonate with greater physical, thermal,

and chemical properties and with only the slightest

yellowish tint. But as stated earlier, polycarbonate needs to

be tinted noticeably purplish to compensate for color shifts

during Gamma sterilization while PESU does not, retaining

its clarity during all sterilization methods.

PESU has excellent clarity, especially in thinner wall

configurations, so it can be colored to transparent and

opaque colors and be more accurately color matched,

provided color constituents can withstand processing

temperatures. Raw material prices for PESU are moderate,

and similar to prices for PEI and PSU. PESU can withstand 4

megarads of Gamma, greater than 1000 steam sterilization

cycles and 100 or more cycles of the other major

sterilization methods (Solvay Specialty Polymers 2016).

PESU is susceptible to environmental stress cracking

due to exposure to certain families of solvents that can

be present in the hospital environment (Solvay Specialty

Polymers 2016). PESU has slightly lower tensile and flexural

properties than PEI but are close enough that PESU can be

a replacement for PEI in many applications.

PEIPEI (polyetherimide) is the final ultra-engineering material

we will be discussing here. PEI is commonly known by

the brand name Ultem. PEI is the highest strength of

the amorphous materials we have covered with higher

tensile strength, flexural strength and hardness than all the

sulfones. PEI’s continuous operating temperature is about

390° F (Saudi Basic Industries Corporation (SABIC) 2016) and

is hydrolytically stable, as well as having better chemical

resistance to many hospital solvents and disinfectants

(Saudi Basic Industries Corporation (SABIC) 2014). These

properties allow PEI to be used in durable products such as

device sheaths, access devices and sterilization tray dividers

and supports. Because of PEI’s strength and durability, it

is also suitable for dental tool parts and fixtures. PEI can

withstand greater than 1000 steam sterilization cycles,

and is suitable for Gamma, EtO and vaporized hydrogen

peroxide sterilization processes (Saudi Basic Industries

Corporation (SABIC) 2014). PEI also has excellent color

stability through hundreds of sterilization cycles (Saudi Basic

Industries Corporation (SABIC) 2014).

PEI has good transparency, so it can be colored to

transparent and opaque colors. Raw material prices for PEI

are moderate, and similar to prices for PSU and PESU.

PEI has a transparent amber appearance which may not

be aesthetically pleasing for some users. This transparent

amber color can limit how well it can be colored, especially

light colors, and may affect how vibrant bright colors may

appear. PEI is attacked by some solvents which can be

present in the hospital environment, this attack can be

exhibited by environmental stress cracking.

Other Ultra-Engineering PolymersThere are a variety of families of ultra-engineering polymers

beyond those discussed in this white paper. These other

high heat polymers tend to fall in similar property ranges

as those defined by PEEK, PPSU, PSU, PESU and PEI. Most

of these other polymer families will have extrusion grades

or grades suitable for extrusion. These other materials are

sometimes formulated for very specific application types or

targeted for certain physical, chemical or thermal properties

and can subsequently have notable processing limitations

that can dictate what types of parts and configurations are

possible and the types of equipment that are necessary to

process them. That is not to say ultra-engineering polymers

other than those listed here should be avoided by any

means, because they can fill in and extend the performance

gaps of the materials discussed here. Utilizing a processor

with experience and knowledge of these other families of

materials will be key to the success of devices specifying

other ultra-engineering polymers.

ConclusionThe materials that we identified here are some of the major

players in the growth of advanced material usage in medical

devices and their components. PEEK, PPSU, PSU, PESU

and PEI have added a level of performance to plastics that

was relatively unknown until not that long ago. Navigating

the properties and differences between them require

those in development and specification roles to gain a new

knowledge set. The goal of this white paper was to provide

a high-level overview of these materials to quickly help

designers gain awareness of the many ultra-engineering

material options available to them. Knowledge of the

variety of ultra-engineering polymers, their properties and

positive and limiting aspects is the solution to unfamiliarity

with these advanced materials and will enable ideal

material selections for medical applications. An additional

requirement for specifying an ultra-engineering material

is to find a processor that has the knowledge, skills, and

experience necessary for converting them to extruded

components. All of these ultra-engineering materials require

specialized extrusion equipment, purpose designed tooling

and the knowledge of unique processing methods that

relatively few extruders have. Apollo Medical Extrusion

Technologies has the experience and techniques necessary

to manufacture complex, high requirement medical device

components utilizing ultra-engineering materials. Being

able to specify the ideal ultra-engineering polymer for

your extruded medical component and having a skilled

processor to manufacture it will open up a brave new world

of medical devices.

About Spectrum Plastics GroupBased in Alpharetta, Georgia with multiple plants across the United States, Mexico, Costa Rica, Ireland, and

Malaysia, Spectrum Plastics Group is a North American leader in the development and manufacture of custom and

specialty plastics products and components for the medical device industry. Spectrum Plastics offers a full range

of custom design, engineering and fabrication services, as well as meet the requirements of ISO 9001, ISO 13485,

and operates multiple Class 7 & Class 8 clean rooms.

For more information, visit spgindustries.com, spectrumplastics.com or contact 404-564-8560.

Works Cited— Saudi Basic Industries Corporation (SABIC). 2014. "Resistance + Durability: Chemical Resistance Performance Testing

for Healthcare Materials." Saudi Basic Industries Corporation (SABIC). 5.

—. 2014. "Resistance + Versatility Ultem HU1004 Resin: A High Performance Resin Blend for Multiple Sterilization

Environments." Saudi Basic Industries Corporation (SABIC). 7 - 9.

—. 2014. "Resistance + Versatility Ultem HU1004 Resin: A High Performance Resin Blend for Multiple Sterilization

Environments." Saudi Basic Industries Corporation (SABIC). 4.

—. 2016. "Ultem Resin." SABIC Innovative Plastics. Accessed April 20, 2016.

https://www.sabic-ip.com/gep/Plastics/en/ProductsAndServices/ProductLine/ultem.html.

— Solvay Specialty Polymers. 2015. "High-Performance Plastics for Healthcare." Solvay Specialty Polymers, March. 3.

—. 2015. "High-Performance Plastics for Healthcare." Solvay Specialty Polymers, March. 6.

—. 2015. "High-Performance Plastics for Healthcare." Solvay Specialty Polymers, March. 5.

—. 2015. "High-Performance Plastics for Healthcare." Solvay Specialty Polymers, March. 2.

—. 2016. "KetaSpire PEEK Design &Processing Guide." Solvay Specialty Polymers, March. 112.

—. 2016. Spire Ultra Polymers - AvaSpire PAEK. Accessed April 20, 2016.

http://www.solvayultrapolymers.com/en/products/avaspire-paek/index.html.

—. 2014. "Veradel HC PESU - Polyethersulfone for Healthcare." Vol. 2.0. November. 21.

—. 2016. Veradel HC PESU. Accessed April 20, 2016.

http://www.solvay.com/en/markets-and-products/featured-products/veradel-hc.html.